linux/fs/debugfs/inode.c

561 lines
16 KiB

[PATCH] VFS: Permit filesystem to override root dentry on mount Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nathan Scott <nathans@sgi.com> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 02:02:57 -07:00
[PATCH] VFS: Permit filesystem to override root dentry on mount Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nathan Scott <nathans@sgi.com> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 02:02:57 -07:00
debugfs: dont stop on first failed recursive delete debugfs: dont stop on first failed recursive delete While running a while loop of removing a module that removes a debugfs directory with debugfs_remove_recursive, and at the same time doing a while loop of cat of a file in that directory, I would hit a point where somehow the cat of the file caused the remove to fail. The result is that other files did not get removed when the module was removed. I simple read of one of those file can oops the kernel because the operations to the file no longer exist (removed by module). The funny thing is that the file being cat'ed was removed. It was the siblings that were not. I see in the code to debugfs_remove_recursive there's a test that checks if the child fails to bail out of the loop to prevent an infinite loop. What this patch does is to still try any siblings in that directory. If all the siblings fail, or there are no more siblings, then we exit the loop. This fixes the above symptom, but... This is no full proof. It makes the debugfs_remove_recursive a bit more robust, but it does not explain why the one file failed. There may be some kind of delay deletion that makes the debugfs think it did not succeed. So this patch is more of a fix for the symptom but not the disease. This patch still makes the debugfs_remove_recursive more robust and until I can find out why the bug exists, this patch will keep the kernel from oopsing in most cases. Even after the cause is found I think this change can stand on its own and should be kept. [ Impact: prevent kernel oops on module unload and reading debugfs files ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-04-25 00:39:40 -04:00
debugfs: dont stop on first failed recursive delete debugfs: dont stop on first failed recursive delete While running a while loop of removing a module that removes a debugfs directory with debugfs_remove_recursive, and at the same time doing a while loop of cat of a file in that directory, I would hit a point where somehow the cat of the file caused the remove to fail. The result is that other files did not get removed when the module was removed. I simple read of one of those file can oops the kernel because the operations to the file no longer exist (removed by module). The funny thing is that the file being cat'ed was removed. It was the siblings that were not. I see in the code to debugfs_remove_recursive there's a test that checks if the child fails to bail out of the loop to prevent an infinite loop. What this patch does is to still try any siblings in that directory. If all the siblings fail, or there are no more siblings, then we exit the loop. This fixes the above symptom, but... This is no full proof. It makes the debugfs_remove_recursive a bit more robust, but it does not explain why the one file failed. There may be some kind of delay deletion that makes the debugfs think it did not succeed. So this patch is more of a fix for the symptom but not the disease. This patch still makes the debugfs_remove_recursive more robust and until I can find out why the bug exists, this patch will keep the kernel from oopsing in most cases. Even after the cause is found I think this change can stand on its own and should be kept. [ Impact: prevent kernel oops on module unload and reading debugfs files ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-04-25 00:39:40 -04:00